Hi
The Sigma 100-300/4 HSM is somewhat of a freak of nature! I have one that I bought mint and sent mine back to Sigma as it was back focusing very slightly! Two trips back and my freak is on. Using it on a D800E and D600 at 100mm f4 it is as sharp as my 105 VR and at 300mm almost the equal of my 300mm f2.8. .
FWIW In my humble opinion their is not a single lens that can take the best value on the planet crown away from the Sigma 100-300mm f4 HSM until they bring out a OS model.

Hi
The Sigma 100-300/4 HSM is somewhat of a freak of nature! I have one that I bought mint and sent mine back to Sigma as it was back focusing very slightly! Two trips back and my freak is on. At 100mm f4 it is as sharp as my 105 VR and at 300mm almost the equal of my 300mm f2.8. .
FWIW In my humble opinion their is not a single lens that can take the best value on the planet crown away from the Sigma 100-300mm f4 HSM until they bring out a OS model.

Hi
The Sigma 100-300/4 HSM is somewhat of a freak of nature! I have one that I bought mint and sent mine back to Sigma as it was back focusing very slightly! Two trips back and my freak is on. At 100mm f4 it is as sharp as my 105 VR and at 300mm almost the equal of my 300mm f2.8. Have to let on that my Nikon 300mm f2.8 is on the B&S and it and the Sigma are nearly equals at half the price..
FWIW In my humble opinion their is not a single lens that can take the best value on the planet crown away from the Sigma 100-300mm f4 HSM until they bring out a OS model.
Now I have done it and let years of research out the bag! Wait till trenchmonkey anf Jonathan find out!